Too many people confuse ‘adaptation’ with ‘evolution’. Humans frequently have to adapt to changing conditions in short amounts of time, for example when they move from one country to another with a different culture. That does not mean they have evolved though, they are still the same person. Evolution is something that happens over millions of years, for example it took us millions of years to evolve from forest-dwelling primates to plains dwelling hunter-gatherers.
However the few tens of thousands of years that have elapsed since the Stone Age are nothing in evolutionary terms. As far as physiology and cognitive functions go, we are still the same Homo Sapiens who used to live in caves and hunt woolly mammoths back in the Ice Age. Life was precarious back then, we didn’t have the benefit of modern technology to protect us from Nature. Man lived in small communities where the males went out to hunt while the females stayed behind and looked after the young. Everyone knew each other by sight (which had taken over from smell as the sense we relied on most), strangers who didn’t ‘look right’ were regarded as enemies and driven away or killed. Infant mortality would have been sky high so any adult who couldn’t or didn’t want to (because for example they were attracted to members of the same sex) breed would have been regarded as harmful to the community. In other words, behaviours that we now call xenophobia, patriarchy and homophobia are hard-wired into us because at the time we evolved into the creatures we are today they were what were needed for the survival of the species. Obviously now that so many of us live in large multi-racial communities called cities in a modern world of sexual equality, we have had to adapt to the changing conditions. But natural instincts, when they are suppressed for the sake of adaptation, have a nasty habit of manifesting themselves in unpleasant ways. See for example the Catholic clergy who have to suppress their natural sex drives to adapt to live in the priesthood. Those looking for a cure for modern ills like racism, sexism and homophobia will find one – in a few million years’ time when those behaviours have evolved out of our nature!